UNITED STATES ENVIRONMENTAL PROTECTION AGENCY

RESEARCH TRIANGLE PARK

, NC 27711

March 2

, 2012



### MEMORANDUM

SUBJECT : Haul Road Workgroup Final Report Submission to EPA-OAQPS

FROM:

# TylerFox,Lead**it- -7~** **J~** Air Quality Modeling Group, C439-01

TO: Regional Office Modeling Contacts OFF I CE OF

AIR QUALITY PLA N N I NG

AND ST A NDA R DS

The challenge of modeling the emissions and associated air qualit y impacts of haul roads

has been a particularly vexing problem for the dispersion modeling community. There is a large degree of uncertainty in the magnitude of these fugitive dust emissions and subsequently in the

modeled estimates at near

- source receptor location s. At the 2009 Regional, State, and Local

Modelers' Workshop, EPA held an interactive session on best modeling practices of haul roads

that was cha i red by Randy Robinson, USEPA Region 5

, and Mick Daye, USEPA Region 7 to

open up a constructive dialog throughout the regulatory dispersion modeling community on the challenges of characterizing and appropriately addressing the haul road fugitive emissions in a compliance demonstration project. Following this 2009 Workshop, the Haul Road Workgroup

was formed with a collection of federal

, state, and local government dispersion modelers. The goal of this Workgroup was to examine and better understand haul road characterization issues

and recommend a modeling methodology back to the broader di s persion modeling community.

The Workgroup decided to focus on the air quality modeling aspects and not address the fugitive

dust emissions factor issues.

A report out of the Haul Road Workgroup was presented at the 2010 Regional, State, and

Local Mode l ers' Workshop. Along with discussion amongst the regulatory dispersion modelers

in attendance at the 2010 Workshop, feedback and comments were solicited and accepted on the

recommendations of the Workgroup throughout 2010 and the first half of 2011. An update presentation on the Workgroup was given at the 20 1 1 Regional, State, and Local Modelers' Workshop with the subsequent release of a draft version of the Haul Road Workgroup Final
Report during the fall of 2011.

Recyc l ed/Recyclable • Printed w H h V egetable OU Based In ks on 1 00".4 Recy cled P aper ( 4 0% Post co nsume r)Attached to this letter is the Haul Road Workgroup Final Report that provides a "best practices guide" for modeling of haul road fugitive emissions in the AERMOD modeling system.

This final report is being shared with the entire dispersion modeling community prior to the 1Oth

Conference on Air Quality Models to promote broader consideration and facilitate further

comment. P l ease send this report to your state, local and tribal agency modelers so that they can provide review and comment, as appropriate. The recommendations presented are not an
endorsement by the USEP A as the definitive methodology for characterizing and addressing fugitive dust emissions from haul roads but should be considered a best practice approach based

on the broad involvement of the co-regulating community in the development of this

recommenda t ion.

We would like to give special recognition to the initiative and labors of Randy Robinson

and Mick Daye in spearheading this initiative in 2009, chairing the Haul Road Workgroup, and developing this final report. We would also like to thank all of the federal, state, and loca l

government dispersion modelers that participated in the Workgroup and assisted in the drafting

of the final report presented in the attachment.

Attachment: Robinson and Daye December 6, 2011 memorandum with Haul Roads Workgroup Final Report included as an attached documentUNITED STATES ENVIRONMENTAL PROTECTION AGENCY

REGIONS

77WESTJACKSONBOULEVARD CHICAGO, IL 60604-3590



## DEC. 

# a 2011 

# '· REPlY TO THE ATTENTION OF'



### MEMORANDUM

SUBJECT:

FROM:

TO: Haul Road Workgroup Final Report

- 

### 1

_. ()
I Randy Robinson, EPA

# Region~**-4~** Mick Daye, EPA Region 7

### ~ 

## ,t(**~** Tyler Fox, Leader, Air Quality Modeling Group George Bridgers, Clearinghouse Coordinator, Air Quality Modeling Group

The purpose of this memorandum is to transmit the attached haul road modeling final
report to the Air Quality Modeling Group. The report represents the collective efforts of the
Haul Road Workgroup, which was formed following the 2009 Regional/State/Local Modeling Workshop. The purpose of the workgroup was to identifY and recommend a technically supportable approach for modeling haul road re-entrained dust.

The attached document contains a summary of the possible options for modeling fugitive·

road dust, a description of the sensitivity modeling conducted by the workgroup, and a tiered set of recommendations for modeling haul road fugitive emissions. The other attachment contains
selected slides from the haul road presentation at the 2010 Regional/State/Local modeling workshop. The Workgroup requests Air Quality Modeling Group review and distribution of the

recommendations document to the modeling community.

Thank you and please contact us if you have any questions or require additional

information.

RocyciOd/Ricyclable • Printed with VeQet!lble Oil Based Inks on 100% Recy<:lett Paper (50% Posloonaumen1 

## Haul Road Workgroup Recommendations

November 2011

Workgroup Charge

-

The Haul Road Workgroup was formally established shortly after the May 2009 Regional/State/Local Workshop. The purpose of the workgroup is to identify and recommend a technically supportable approach for modeling haul road re

- entrained dust. While emission factors are a critical part of any roadway modeling exercise, this workgroup felt that emissions were outside our scope and did not engage i n a review or evaluation of available fugitive dust emission factors. Based on modeling work and field study/journal article review, the following represents a recommendation for an approach to characterizing haul road fugitive emissions in AERMOD.

So urce Characterization

- The model to be used for modeling h aul road fugitive dust emissions is AERMOD. There are several ways haul road fugitive dust emissions can be
characterized in AERMOD , including area source, volume source, and series of point

sour ces. A line source algorithm is being developed but is not currently available. Each approach has advantages and disadvantages. The workgroup has considered each approach and a summary of the strengths and weaknesses is presented below.

Area source ad vantages:

Can place receptors in ambient air contained within the area source Easy to replicate dimensions of roadway in X and Y coordinates Avoids the need to determine Sigma Y values (Sigma Z values are optional) Can utilize a Sigma Z value if desired, to reflect a n initial, well

- mixed plume Area sources explicitly simulate a uniform emission density across the roadway, which may be more realistic in some respects than other approaches.

Area source disadvantages:

Area source in AERMOD does not have the meander algorithm

Run times are generally longer than other approaches

Volume source advantages:

Volume source in AERMOD contains meander algorithm Conceptually, a volume source mimics a n initial

, well

- mixed plume Potentially f

aster run time than area source2

Volume source disadvantages:

Concentrations are not calculated in a volume source exclusion zone

o Exclusion zone is the region ( (2.15 x Sigma Y) + 1 meter)) from the
center of the volume.

Point Source with downwash advantages :

Prec ludes the need to establish Sigma values; handled internally by downwash Conceptually, consistent with well

- mixed plume Can place receptors anywhere within roadway Can be used for buildings near roadways

Point source with downwash disadvantages :

Downwash algorithm in AERMOD does not contain meander for receptors within
the wake Technique would be new to modeling community Additional assumptions required , including building (truck) size, stack temp,
vel ocity , height. Potential issues with BPIP used in this technique



### S ensitivity analysis

Early in the process, the workgroup conducted a n AERMOD sensitivity analysis to examine changes in haul road characterization inputs using volume and area source techniques

. Limited, preliminary point source technique sensitivity runs were also
conducted. Details of th e sensitivity analyse s are available at http://www.cleanairinfo.com/regionalstatelocalmodelingworkshop/archive/2010/Docume nts/Presentations/RSL2010_HaulRoads.pdf

. The following summarizes the setup and general conclusions.

Analysis setup:

 Used AERMOD Version 09292

 1 yea r of meteorological data (variety of locations)

 N

- S and E

- W crisscrossing road segments. Each 500m long, 10m wide.

 Flat Terrain

 Receptor Grids

– Cartesian and Polar; beginning as near as possible to the volume sources. 1 meter from edge of area source. No receptors within source.

 Unit emission rate

 Evaluated range of values for top of plume height, Sigma Z, Sigma Y, and release height.

 Modeled using Adjacent Volume, Alternate Volume, and Area source representations.3

 Calculated results for annual ave , peak 1

- hr, 8 th H 1

- hr, peak 24

- hr, 8 th H 24

- hr

 Point source modeling examined single vs multiple stacks and varying stack
parameters.

General Conclusions:

 Increasing release height ( and related Sigma Z ) led to lower concentrations.

 Increasing Sigma Y for alt ernate and adj acent volume sources lowered
concentrations.

 For area source

– increasing X dimension lowered concentrations at low er release heights (i.e., 0m and 0.5m) . It had little impact at higher release heights (i.e, 1.5m and 3m)

.  For area source

– adding a S igma Z lowered concentrations for surface release heights, but generally increased concentrations at higher release heights

 F or volume runs, adjacent gives higher concentrations than alternate.

 Point Source

– limited

, preliminary modeling shows some sensitivity to stack height and velocity

 On

- site met eorological data model runs showed same trends as with National Weather Service data, although concentrations were higher with on

- site data

.



### Model/Monitor Comparison

The workgroup was interested in locating field data to facilitate our review of haul road dispersion characteristics. Finding field data relevant to our task was difficult. While there are numerous field studies relevant to haul roads, the vast majority deal with monitoring designed to evaluate haul road emissions rather than dispersion
characteristics. An evaluation conducted by OAQPS in 2006 examined haul road emissions from the Cordero Rojo Mine in Eastern Wyoming. The modeling looked at
volume and area source configurations in AERMOD. The study, while limited, showed volume source characterizations performing slightly better than area source when compared to monitored PM10 data. The analysis was primarily designed to examine the impact of the m eander algorithms. This is significant because the volume source approach incorporates meander while the area source approach does not. The difference in model performance was attributed to area source over

- estimates due to lack of meander upwind disper sion. Details of the Cordero Rojo Mine evaluation results can be
found at http://www.awma.org/events/confs/AQMODELS06/Session%204/4

- Roger%20Brode.pdf

.4



### Haul Road Recommendations

Definitions

During the workgroup discussions and sensitivity modeling work, the following definitions were used;

“VH” means vehicle height [~3m for typical haul trucks; ~10m for large mining trucks]
“VW” means vehicle widt h [~3m for typical haul trucks; ~10m for large mining trucks] “VL” means vehicle length [~10m for typical haul trucks; ~20m for large mining trucks]

These definitions and associated dimensions were useful to the group as we discussed the various methods and developed the inputs to be used in the sensitivity modeling. They should not be treated as default values and/or used in place of site specific dimensions available for individual modeling demonstrations.

General Recommendation

The following represents a general recommendation for modeling of haul road emissions.
The recommendation is not meant to be prescriptive ; local conditions and specific information may lead to an alternative approach. However, the workgroup feels that the recommendation presented below is reasonable, can be technically supported, and provide s a level of conservativeness given the large amount of uncertainty associated with characterizing and simulat ing dispersion of fugitive emissions resulting from h aul
road traffic. Concentrations must be calculated in areas that are considered ambient air. 1

Volume Source

– Recommend for all haul roads, except for cases where ambient air receptors are within the volume’s exclusion zone (i.e., ( ( 2.15 x Sigma Y) + 1 meter)) from the center of the volume.

Rationale: Volume source contains the meander algorithm. Conceptually fits the physical parameters associated with well

- mixed plume.

L imited model/monitor comparison study information suppo rts volume source

Recommended Volume Source Configuration:

o Adjacent Volume Source

1 Ambient Air is defined at 40 CFR Part 50.1(e) and further clarified in a December 19, 1980 from Douglas Costle to Senator Jennings Randolph. See http://www.epa.gov/scram001/guidance/mch/ama4.txt5 o Top of Plume Height 2

– 1.7 x VH

o Volume Source Release Height

– 0.5 x T op of P lume height

o Width of Plume

– VW + 6m for single lane roadways / Road Width + 6m
for two lane roadways 3

.

o Initial Sigma Z

– Top of Plume / 2.15 AERMOD User’s Guide , Table 3

- 1 for use when modeling multiple volumes.

o Initial Sigma Y

– Width of Plume / 2.15 AERMOD User’s Guide , Table
3

- 1

o Emissions input as g/s

The 1.7 factor in the Top of Plume Height equation above is supported by information in a 2005 Atmospheric Environment paper by Gillies, et. al, entitled Effect of Vehicle Characteristics on Unpaved Road Dust Emissions.

The Width of Plume value is based on a conservative adaptation of monitor placement guidance from EPA’s 1992 document, Guideline for Modeling Carbon Monoxide from Roadway Intersections. In that document, it is recommended that monitors not be placed nearer than 3 meters from the roadway edge to account for
vehicle turbulence . Two

- lane roadways are for cases with heavy two

- way traffic where the combined plume needs to be approximated. Agencies may need to consider traffic counts, vehicle width, road width, and the amount of two

- way traffic, in order to determine whether the roadway is best represented using single

- lane or

two

- lane assumptions. While the workgroup’s sensitivity analysis indicates increased volume source width leads to decreased concentrations, our group didn’t speci fically examine single

- lane versus two

- lane roadways. One option is to model

two

- lane roadways as two

, single

- lane volume sources. For cases where ambient air receptors fall within the volume source exclusion zone, a
conservative volume source approach would be to reduce the width of plume dimensions enough so that the ambient air receptors are not inside the exclusion zone. Additionally, a mix of area sources and volume sources may adequately allow for consideration of all ambient air receptors.

Ar ea Source

– Recommended for haul roads where ambient air receptors are
located within source dimensions.

Rationale: Volume source doesn’t allow placement of receptors within exclusion zone

. Area source can calculate concentrations at receptors within s ource. Area source can simulate volume source with use of similar release height and Sigma Z parameters.

2 Gilli es, J.A., V. Etyemezian, H. Kuhns, D. Nikolic, D.A. Gillete, 2005. Effect of Vehicle Characteristics on Unpaved Road Dust Emissions. Atmospheric Environment, 39, 2341

- 2347

3 EPA. 1992. Guideline for Modeling Carbon Monoxide From Roadway Intersections. EPA

- 454/R

- 92

- 005. http://www.epa.gov/scram001/guidance/guide/coguide.pdf6

Recommended Area Source Configuration

o Length

– length of roadway segment (Aspect ratio in AERMOD extended to 100:1 before warning is issued. Se e Model Change Bulletin #3, Miscellaneous item #10)

o Width

– VW + 6m for single lane / Road Width + 6m for two

- lane (same comment as for volume, two single

- lanes is an option )

o Top of plume height

– 1.7 x VH

o Release height

– 0.5 x top of plume height

o Sigma Z

– Top of Plume height / 2.15

o Emissions input as g/s/m 2

Point Source

– The workgroup is not forwarding any point source recommendation
at this time . There are potential benefits to this approach, however, more study is
needed.



### Future Efforts

The workgroup understands that efforts are underway on a line source algorithm t o be included in AERMOD. The time frame for completion of this work may be within the next couple years. A new line source algorithm would likely supplant the need to model haul road fugitive dust emissions using either volume, area, or point sources.

Point source modeling of fugitive roadway emissions has some potential benefits, as noted earlier in this paper. One example is the ability to consider the influence of fac ility structures located near roadways when simulating the roadway fugitive dust in AERMOD. The Haul Road Workgroup supports further study of this approach.

More field studies examining initial plume dimensions are encouraged. The effects of
vehicl e speed on the initial plume dimensions is an area that should be investigated when, or if, more field studies are conducted.7



### References

Brode, R.W., Improved Algorithms for Modeling Impacts Near Roadways. MACTEC Federal Programs, Inc. A&WMA Specia lty Conference, Denver, CO, April 2006

EPA. 1992. Guideline for Modeling Carbon Monoxide From Roadway Intersections.
EPA

- 454/R

- 92

- 005. http://www.epa.gov/scram001/guidance/guide/coguide.pdf

EPA. 1994. Modeling Fugitive Dust Impacts from Surface Coal Mining Operations

– Phase II. EPA

- 454/R

- 94

- 025

Eskridge, R. E., Thompson, R.S., 1982, Experimental and Theoretical Study of the Wake
of a Block

- Shaped Vehicle in a Shear

- Free Boundary Flow. Atmospheric Environment, 16, 2821

- 2836

Fitz, D. R., 2001. Measurements of PM10 and PM2.5 Emission Factors from Paved
Roads in California. Contract No. 98

- 723. California Air Resources Board, Monitoring and Laboratory Division

Gillies, J.A., V. Etyemezian, H. Kuhns, D. Nikolic, D.A. Gillete, 2005. Effect of V ehicle Characteristics on Unpaved Road Dust Emissions. Atmospheric Environment, 39, 2341

- 2347

.

Guideline on Air Quality Models, US Environmental Protection Agency, 40 CFR Part 51, Appendix W, November 9, 2005.

Heinerikson , A., Goodman, A., Anderson, K., Analysis of Haul road Emission Test Data for Determining Dispersion Modeling Parameters. Trinity Consultants.

Reed, W. R., Performance Evaluation of a Dust

- dispersion Model for Haul Trucks. National Institute for Occupa tional Safety and Health, Pittsburgh Research Lab.

User’s Guide for the AMS/EPA Regulatory Model

– AERMOD, US Environmental Protection Agency, EPA

- 454/B

- 03

- 001, September 2004.

Westbrook, J.A., Sullivan, P.S., Fugitive Dust Modeling with AERMOD for PM10
Emissions fro m a Municipal Waste Landfill.

Williams, D.S., Manoj, K.S., Ross, J., Particulate Matter Emission by a Vehicle Running on Unpaved Road. 2008. Atmospheric Environment, 42, 3899

- 3905.1



### Select Slides from May 2010 Regional/State/Local Workshop Presentation234567

MAX. CONCENTRATION

- 89 ug/m3891011 POINT SOURCE WITH DOWNWASH12